Electrically fired percussion primer



Oct. 4, 1955 A. M. STOTT ELECTRICALLY FIRED PERCUSSION PRIMER Filed May 51, 1950 FIG. I.

j /6 a4 38 3o 29 27 32 c /7 39' 35 26 as 22 26 23 44 FIG. 2.

IN V EN TOR.

ALBERT M. STOTT.

ATTORNEYS.

United States Patent ELECTRICALLY FIRED PERCUSSION PRIMER Albert M. Stott, Aldan, Pa.

Application May 31, 1950, Serial No. 165,283

1 Claim. (Cl. 89--28) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described in the foregoing specification and claim may be manufactured and used by or for the Government for governmental purposes without the pay ment to me of any royalty thereon.

This invention relates to primers for detonating explosive cartridges, and has particular reference to electrically operated means for detonating artillery percussion type primers.

Broadly stated, the object of the present invention is to provide an electrically operated mechanism for detonating percussion primers, said mechanism to be readily interchangeable for use in various guns, explosively actuated catapults, disaster beacons, and the like.

A more specific object is to provide a simple, economical and effective device for electrically detonating a conventional percussion type primer under conditions which closely simulate conventional conditions of detonation for such primers.

Another object is the provision of a priming device which enables uniform firing with a minimum time lag, and operates with a minimum of difiiculty or failure.

A further object is to provide a priming device which is inexpensive to produce and maintain in good working order.

I attain the foregoing and other objects by providing a universal electric firing head mounted in an adapter suitable for installation in a gun or other explosive-actuated propelling device. In the firing head there is mounted a conventional electric primer and means for electrically igniting same. The adapter is provided with an axial passageway that provides a means of communication between the electric primer and a conventional percussion primer which is located in the gun. Although not altogether necessary, in some adaptations of my invention I provide a plunger which, by virtue of the force of the gases developed upon ignition of the electric primer, can be drivenagainst the percussion primer to cause it to detonate. Otherwise, when no plunger is employed, the electric primer can be so adapted that the gases developed thereby will provide a shock wave which impinges upon and thus detonates the percussion primer. h

The construction of my novel device'will be seen from the drawings, wherein:

Fig. 1 is a longitudinal section through my unique mechanism, illustratively shown as mounted in the breech of a rear-venturi type recoilless gun; and

Fig. 2 is a similar, but enlarged section through the universal firing head and a portion of the adapter.

The illustrated gun 6 has a breech block 7 and chamber 8. Supported in the chamber is a cartridge case 9 in whose head 10 is mounted a conventional percussion type primer 11.

In breech block 7 is removably mounted an adapter 14. The external shape of this adapter is not critical, and it may take any convenient form, such as that illustrated in the drawings, by which it may be bush-fitted in the breech block. To retain the adapter within the block any preferred conventional means may be employed, as,

2,719,458 Patented Oct. 4, 1955 for example, by means of a screw (not shown) whose head fits into an accommodating recess (not shown) in the block and in a flange portion 15 of the adapter.

For ease of reference, it will be convenient to refer to the front end of the adapter as being that which faces the percussion primer 11, and the rear end as being the opposite extremity thereof. At the adapters rear end there is provided a relatively large interiorly threaded cylindrical recess 16. A cylindrical passageway 17 axially extends forwardly from the front end of recess 16 through the remainder of the adapter.

A universal electric firing head 18 is provided, its metallic housing 19 taking any suitable form such as the T-shape illustratively shown in the drawings. The stem portion of the housing is threadedly connected, as indicated at 20, to the interior of recess 16, while the crossbar portion projects to the rear of the adapter. This head 18 has extending axially therethrough a cylindrical recess 21 of three different diameters, the smallest being at the rear end and separated by a shoulder 22 from the next larger one which is in turn separated by a shoulder 23 from the largest diameter that opens to the front end of the head.

Filling the smallest and intermediate diameters of recess 21 is a cylindrical contact pin 26 which is hollow except for a forwardmost conical point 27 that juts out from a flange-like portion 28. This flange fills the intermediate diameter of recess 21 and, in conjunction with shoulder 22 in housing 19, serves to restrain contact pin 26 against further rearward movement and thus aids in locating the pins position in the head. To assure that gases do not leak past the juncture of shoulder 22 and flange 28, a seal may suitably be provided there by wrapping a few turns of dental floss 29 around pin 26 adjacent the flange. Encasing the external cylindrical wall of pin 26, even covering over the dental floss gas seal, is any suitable insulating material 30 such as a plastic or other preferred dielectric coating.

A washer 31, made of insulating material such as rubber or the like, fills the rearmost region of the largest diametered portion of recess 21, abutting against shoulder 23 and also against the forward face of pin 26 but leaving space for conical point 27 to protrude therethrough. In front of washer 31 is a conventional electric primer 32 which is maintained in contact with conical point 27 by means of a primer retainer 33 that is threadedly secured to head 18 as indicated at 34. Retainer 33 has an axial passageway 35 therethrough which is of equal size and confluent with passageway 17 extending through adapter 14.

- As above said, except for conical point -27, cylindrical contact pin 26 is hollow. Filling that hollow cavity, which serves as an electrical jack, is an electrical connecting plug 38 carrying a conventionally insulated electricity conducting wire 39 that leads to an electric current source 40 interrupted by an electric switch 41. Similar provision is made for the ready insertion of another electrical plug 43, carrying electric wire 44, into the cross bar portion of the T-shaped head 19. Wire 44 is grounded in any convenient manner as at 45.

It will be noted from the above construction details that a complete electrical circuit is provided for detonating electric primer 32. Current, supplied from source 40, passes through closed switch 41 (shown open in Fig. 1), wire 39, conical point 27, primer 32, primer retainer 33, firing head 18, wire 44 and thence to ground 45 to complete the circuit. Insulating material 30 and the rubber Washer 31 of course serve to prevent a short circuit which otherwise would develop across the closely adjacent metallic parts of the firing head.

In operation, switch 41 is closed and electric primer 32 is detonated as just described. The resulting explosive games build up a static pressure and also a dynamic pressure, both confined inpassageways- 17 and 35- so' as directly to act upon and thereby detonate the percussion primer 11 which is adjacent to the forward exit of those passageways. In such cases the percussion primer preferably should be of the we'll known artillery type having a" selfcontained firing plug (not shown). Such direct action is particularly desirable incases where, for one reason or another, passageway 17 follows a tortuous or twisted path (not illustrated), or when it is disposed at an angle (also not shown) to the axis of the bore in which the percussion primer is situated. But in applications such as that shown in the drawings, wherein passageway 17 is parallel with the axis of the gun, it is sometimes desirable to employ a plunger or firing plug 47.

This plunger may be located at some distance behind percussion primer 11 by any convenient means such as a resilient clip (not shown) therearound, or even more simply by' magnetizing the plunger so that it will stay fixed where placed until suddenly and forcefully urged forward; in response to the energy of the gases from the electric primer, to detonate the percussion primer. Plunger 47 has a well-rounded leading end which is especially so designed in order to avoid piercing percussion primer 11. Piercing of the primer would cause an undesirable rearward leakage of powder gases that is both ineflicient and causes fouling of the testing mechanism. A major contributing factor to controlling the impact given primer 11 so as to prevent its being pierced is the ability readily to adjust the distance which plunger 47 is to travel before striking that primer. This makes it possible, for any selected mass which the plunger may possess and for any selected amount of resistance to impact which the cup of primer 11 may possess, to regulate the blow given that primer to obtain the optimum amount of indentation without breaking through the primer cup and further so as to cause the cup to obturate, thereby aiding in preventing rearward leakage of powder gases.

With an understanding of the foregoing construction it is a relatively simple matter for persons skilled in the art to envisage numerous modifications thereof which will yet remain within the scope of the present invention. For example, if it should be desired to operate timing instruments or other devices in conjunction with the firing, the firing switch 41 can be made to control the circuits of those other devices so that the detonation and recordation' will be simultaneous. If a number of weapons of the same or different calibers are to be fired simultaneously, all the electric primers may be interconnected for concerted action. If necessary, the amount of energy required for detonating the percussion primer may be boosted over that normally supplied by the electric primer either by adding one or more booster charges or by using more than one electric primer per each percussion primer.

Although this invention may be employed in actual combat or other repetitive firing usages of guns and the like, it willundoubtedly be found to be most advantageous when employed in one-shot devices such as are used in ballistic laboratories, or in airplane or ship disaster beacons, etc. When employed in test weapons, there are certain specialadvantages to be derived (in addition to obvious utility and economy for general applications) inasmuch as the universal firing head may be used in many diflerent applications simply by changing the adapter to suit a particular need. Other obvious, more general advantages, are the assurance of uniform firing with a minimum time lag, and the assurance of relatively trouble-free operation due to the comparatively few working parts which also makes the device compact and cheaper to produce, install, maintain and operate. A further advantage is the fact that a considerable amount of head space behind the percussion primer can be tolerated, and no sealing of the electric primer gases at this point is necessary.

From the foregoing it will be seen that I have provided an electrically operated mechanism for detonating percussion primers, said mechanism being interchangeable for use in various guns, explosively actuated catapults, disaster beacons, and the like; that I have provided a simple, economical and effective device for'electrically detonating a conventional percussion ty'pe primer under conditions which closely simulate conventional conditions of detonationv for such primers; that I have provided a priming device which enables uniform firing with a minium time lag, and operates with a minimum of difficulty or failure; and that I- have provided a priming device which is inexpensive to produce and maintain in good working order.

To persons skilled in tha art it will further be apparent that the present invention is extensive in its adaption and is not to be limited to the above specification or accompanying illustrations, but only by the claim appended below.

I claim:

An electrically fired gun comprising: a barrel adapted to accommodate an ammunition round; a breech block removably fitting inside said barrel for supporting the head end of the ammunition round; an adapter in said breech bl'ock'; an electric detonator in said adapter; firing means for said detonator; and a firing plug fitted for axial movement in said adapter; whereby, upon operating said firing means, said electric detonator explodes and moves said firing plug energetically against the ammunition round with sufiicient momentum to fire the ammunition.

References Cited inthe file of this patent UNITED STATES PATENTS 922,268 Dawson May 18, 1909 1,197,729 Flather Sept. 12, 1916 1,318,954 Barlow Oct. 14, 1919 1,335,500- Hasting Mar. 30, 1920 2,041,209 Ridley May 1-9, 1936 2,359,517 Gebeau Oct. 3, 1944 2,397,781 Fischer Apr. 2, 1946 2,436,396 McCaslin' Feb. 24, 1948' FOREIGN PATENTS 610,106 Great. Britain Oct. 12, 1948 614,381 Great Britain Dec. 14, 1948 

